This invention relates to a composition for an anti-reflective coating or a radiation absorbing coating useful for forming an antireflective coating or other radiation absorbing coating, a monomeric dye, a polymeric dye or a hardening agent compound being used in the composition, a method of forming an anti-reflective coating or a radiation absorbing coating and a method of preparing resist patterns or integrated circuits using the anti-reflective coating or radiation absorbing coating.
In the field of semiconductor manufacturing, to obtain integrated circuits with a higher degree of integration, miniaturization techniques of resist pattern size have been studied and development and improvement of lithographic processes using short wavelength exposure tools such as deep ultraviolet ray are proceeding. High performance resist showing good properties on deep ultraviolet exposure, as positive- or negative-working chemically amplified photoresists sensitive to deep ultraviolet (100-300 nm) are known. While such exposure tools in combination with the high performance chemically amplified resists are capable of patterning sub-quarter micron geometry, they bring in several other problems that need to be solved in achieving such high resolutions. One such problem which is well known in the art and is called xe2x80x9cstanding wavesxe2x80x9d arising from interference with incident beam and reflective beam reflected on the surface of the substrate. Another limitation is the difficulty in uniformly controlling the linewidth of the resist pattern in a single layer resist process due to thin film interference effects resulting from highly planar and non-planar substrates. Such problems are well documented. See, for example, M. Horn in Solid State Technology, November 1991, p. 57, and T. Brunner, Proc. SPIE, vol.1466, p.297 (1991). Other pattern distortions are caused by light reflected angularly from topographical features, which is called reflective notching and are discussed by M. Bolsen, G. Buhr, H. Merrem, and K. Van Werden, Solid State Technology, February 1986, p.83.
One method to overcome the above-mentioned problems is to add dyes to the photoresists as described in U.S. Pat. No. 4,575,480, U.S. Pat. No. 4,882,260 and so on. When a dye is added to the photoresist to form a photoresist film having high optical density at the exposing wavelength, drawbacks such as loss of resist sensitivity, difficulties during hardening processes, thinning of the resists in alkaline developers and sublimation of the dyes during baking of the films are encountered. Another technique to overcome the problem of forming patterns on reflective topography is a top surface imaging (TSI) processes or multilayer resists (MLR) as described in U.S. Pat. No. 4,370,405. Such methods help to prevent the problems associated with reflectivity but are not only complex but also expensive and not a preferred method. On manufacturing semiconductors, single layer resist (SLR) processes are used commonly because of their simplicity and cost-effectiveness.
Another method to eliminate the interference of light is to reduce the substrate reflectivity through the use of so-called bottom anti-reflective coatings (hereinafter abbreviated as BARC). These coatings have the property of absorbing the light which passes through the photoresist and not reflecting it back. As these coatings, two types, inorganic and organic types are known. Inorganic type include such coatings as TiN, TiNO, TiW and inorganic polymer in the thickness of 300 xc3x85. See, for example, C. Nolscher et al., Proc. SPIE, vol.1086, p.242 (1989), K. Bather, H. Schreiber, Thin Solid Films, 200, 93 (1991) and G. Czech et al., Microelectronic Engineering, 21, p.51, (1993). Other examples of inorganic coating are of titanium, chromium oxide, carbon and xcex1-silicon. These inorganic anti-reflective coatings are usually formed by a vacuum evaporation process, a CVD process, spattering and so on. The inorganic anti-reflective coatings,however, have such problems as require precise control of the film thickness, uniformity of film, special deposition equipment, complex adhesion promotion techniques prior to resist coating, separate dry etching pattern transfer step, and dry etching for removal. Some of inorganic coatings show conductivity. The conductive coating is not available for anti-reflective coating upon manufacturing integrated circuits.
Organic anti-reflective coatings have been generally formulated by adding dyes which absorb at the exposure wavelength to a polymer coating (Proc. SPIE, Vol.539(1985), p.342). The organic anti-reflective coating can be formed on a substrate by the same method as resist coating and, therefore, need not use special apparatus. Problems of such dye blended coatings include (1) separation of the polymer and dye components during spin coating, (2) migration of dye into resist solvents and (3) thermal diffusion into the resist upon the baking process. All these cause degradation of resist properties and therefore the method of forming an anti-reflective coating by using a polymer coating composition containing a dye is not a preferred method.
Chemically binding the dyes into film forming polymers is another method. Fahey, et al. (Proc. SPIE, Vol. 2195, p.422) propose to use amino group possessing dyes reacted with the acid anhydride groups of poly(vinyl methylether-co-maleic anhydride) as anti-reflective coating materials. The problem with this type of anti-reflective coating composition is that the reaction between amine and the acid anhydride group is not always 100% complete and this leads to the presence of free amines (refer EP 0583205, page 5, lines 17-20). The free amine causes poisoning of the resist at the interface between anti-reflective coating and resist, especially when a chemically amplified resist composition is used and this leads to a problem called footing. The free dye molecules also sublimes during the baking process and deposits on the fabrication instruments and causes contamination problem as well as health hazard to the workers. One more problem of such compositions is that imide compounds are poor in their solubility and need polar solvents normally not used in photoresist formulations. It would be ideal to have the similar solvent as the photoresist for anti-reflective coating for the reason that the photoresist and anti-reflective coating are often formed using the same coater. Further, fine particles are formed in the coating composition due to the by-product of the imidization reaction, water, to cause defects in the resist pattern.
In addition, Fahey et al. proposed another anti-reflective coating material based on a copolymer of methyl methacrylate and 9-methylanthracene methacrylate. However, when using a chemically amplified resist, this system also shows footing problems due to the diffusion of photo-generated acid into the anti-reflective coating (Proc. SPIE, Vol.2195, P.426) as well as intermixing of the resist and the anti-reflective coating. Such polymers are also insoluble in preferred solvents in the art, such as propylene glycol monomethyl ether acetate (PGMFA) and ethyl lactate.
U.S. Pat. No. 5,234,990 reports polysulfone and polyurea polymers which possess inherent light absorbing properties at deep ultraviolet wavelengths. These condensation products have poor film forming properties on a patterned wafer, and therefore, bad step-coverage and the formation of cracks perhaps due to high Tg and rigid structures of such polymers. Ideally, a bottom anti-reflective coating materials should form a soft layer with good step coverage property upon coating and also harden at least after baking, to prevent intermixing of the photoresist and anti-reflective coating layer as well as diffusion of the photo-generated acid.
Yet another European Laid-open Patent application No. 542 008 describes the use of phenolic type resin binders and melamine type cross linkers in combination with thermal or photo acid generators to harden the anti-reflective coating film after coating. Such compositions are poor in their shelf-life stability due to the presence of the cross-linkers and photo acid generators leading to high incidence of film defects and their etch rate is very slow due to the presence of large amounts of aromatic functional groups.
In summary, a good bottom anti-reflective coating material should satisfy the following properties:
(a) good film forming property
(b) high absorption at the desired exposure wavelength
(c) no intermixing with the photoresist
(d) etch-rate much higher than the photoresist
(e) good step-coverage on topography
(f) at least six months shelf-life stability
(g) the composition should be dissolved in a edge-bead rinse (EBR) solvent
Unfortunately none of the present bottom anti-reflective coating (BARC) materials satisfy these properties.
The present invention provides materials with the above-mentioned properties which are necessary for a good BARC material; a composition available for forming a BARC which contains the BARC material; a method of preparing thereof; a BARC layer formed by using the materials or composition; a method of forming thereof; and preparing resist patterns or integrated circuits.
The first object of the present invention is to provide a composition capable of forming a bottom anti-reflective layer or a radiation absorbing layer which reduces problems associated with reflected light from the substrate and topography during pattern formation.
The second object of the present invention is to provide a composition capable of forming a bottom anti-reflective coating or a radiation absorbing coating with improved adhesion to substrates for a micro-circuit, very good coating uniformity and no particle formation.
The third object of the present invention is to provide a composition capable of forming a bottom anti-reflective coating or a radiation absorbing coating that has a higher etch rate than the photoresist material applied thereon.
The fourth object of the present invention is to provide novel (co)polymeric materials applicable for bottom anti-reflective coatings or radiation absorbing coatings containing intrinsically cross-linking and highly absorbing functions in a single molecule and which are soluble in similar or the same solvent as the photoresist material applied thereon. The fifth object of the present invention is to provide novel (co)polymeric materials applicable for bottom anti-reflective coatings containing intrinsically cross-linking and highly absorbing functions in a single molecule, eliminating the need for additives with such functions.
The sixth object of the present invention is to provide novel monomers, polymers and copolymers capable of curing (cross-linking) at the baking temperatures to form very hard layers after baking, the resulting anti-reflective coating having no intermixing with photoresist coated thereon and no diffusion of the acid generated in the subsequent exposure steps to the anti-reflective coating and thereby preventing footing.
The seventh object of the present invention is, to provide novel monomers, polymers and copolymers containing chromophores highly absorbing exposed wavelengths and being able to form ultra-thin anti-reflective coatings, which can provide sufficient radiation absorption with a film thickness of 30-300 nm.
The eighth object of the present invention is to provide an anti-reflective coating or a radiation absorbing coating with good radiation absorbing property.
The ninth object of the present invention is to provide a method of easily producing resist patterns with high resolution.
The tenth object of the present invention is to provide a method of easily manufacturing integrated circuits with a high degree of integration.
Further objects of the present invention will become apparent from the following description.
The composition for anti-reflective coating or radiation absorbing coating of the present invention is characterized by containing at least one member selected from, monomers or polymers represented by the following General Formula I or II. 
Wherein
R is a hydrogen atom or an alkyl group; R1 is an alkylene group, a substituted alkylene group, a cycloalkylene group, a substituted cycloalkylene, group, a phenylene group or a substituted phenylene group, R2 is a phenyl group, xe2x80x94COOH, a halogen atom, a cyano group, an alkoxyl group, xe2x80x94COOR6 in which R6 is a substituted or non-substituted alkyl or aryl group or an ethylacetoacetate group; R3 is xe2x80x94COOD; D is an organic chromophore which absorbs the exposed wavelength (100-450 nm) and represents a substituted or non-substituted, benzene ring, condensed ring or heterocyclic ring bonded directly or through an alkylene group, X is O or S, Y is O or NR4 group in which R4 is either a hydrogen atom or a substituted or non-substituted, phenyl group or cyclic, linear or branched alkyl group, Z is O, ND group or NR5 group in which R5 is either a hydrogen atom or a substituted or non-substituted, phenyl group or cyclic, linear or branched alkyl group and n, p and q are simple integers including zero and m and o are also simple integers including zero while at least one of them is greater than zero.
Above mentioned composition is coated on a reflective semiconductor substrate such as silicon primed with hexamethyl disilazane, for example, in dry thickness of 300-50,000 xc3x85, baked to evaporate the solvent and harden the film, a thin film being formed. The baking temperature of the film is usually in the range of 50 to 250xc2x0 C. Then a desired photoresist is coated onto the film, exposed through a mask and developed to produce a resist pattern with predetermined line width. The pattern is transferred to the substrate by dry- or wet-etching the resist pattern. Thus integrated circuit with a high degree of integration are manufactured.
Monomers of the present invention represented by the above mentioned General Formula I can be synthesized from a bifunctional monomer represented by the following General Formula III. 
Wherein R, R1 and X are as defined above.
It is possible to prepare a variety of monomeric dyes C possessing polymerizable vinyl groups by reacting the bifunctional monomer A represented by General Formula III with amino or hydroxyl group containing chromophore B as shown in the following Reaction Scheme I. 
Wherein R, R1, X, Y and D are as defined above.
As examples of D, the following groups are given but by no means limited to these examples: phenyl, substituted phenyl, benzyl, substituted benzyl, naphthalene, substituted naphthalene, anthracene, substituted anthracene, anthraquinone, substituted anthraquinone, acridine, substituted acridine; azobenzene, substituted azobenzene, fluorene, substituted fluorene, fluorenone, substituted fluorenone, carbazole, substituted carbazole, N-alkylcarbazole, dibenzofuran, substituted dibenzofuran, phenanthrene, substituted phenanthrene, pyrene, substituted pyrene and so on. The substitutions in D can be one or more of the followinggroups. That is, alkyl, aryl, halogen, alkoxyl, nitro, aldehyde, cyano, amide, dialkylamino, sulfonamide, imide, carboxylic acid, carboxylic acid ester, sulfonic acid, sulfonic acid ester, alkylamino, arylamino and so on.
As examples of compound A in the Reaction Scheme I which is represented by General Formula III, the following compounds are given: 2-isocyanatoethyl methacrylate, 2-isocyanatoethyl acrylate, 4-isocyanatohexyl acrylate, 4-isocyanatobenzyl methacrylate, 3-isocyanatopropyl methacrylate and corresponding compounds which isocyanate group therein is replaced with thioisocyanate group. Preferred examples of compound A include 2-isocyanatoethyl methacrylate and 2-isocyanatoethyl acrylate. Preferred examples of compound B in the reaction scheme I include but by no means restricted to the following: phenol, benzyl alcohol, 4-hydroxybiphenyl, 4-hydroxybenzaldehyde, 7-hydroxy-2-naphthaldehyde, 9-hydroxyanthracene, 9-hydroxymethhylanthracene, phenanthrol, aniline, benzylamine, 2-phenylethylamine, 4-aminobenzenesulfonamide, 4-aminobenzophenone, 4-aminobenzylcyanide, 4-aminobenzoic acid, 4-aminobenzanilide, 4-aminobiphenyl, 1-aminonaphthalene, 1-aminoanthracene, N-(2,4-dinitrophenyl)-1,4-benzenediamine, 4-N,N-dimethylbenzenediamine, 4-aminophenol, 4-aminodiphenyl ether, 4-aminoquinoline, etc. Especially preferred examples of compound B include 1-aminoanthracene, 1-aminonaphtalene and 9-hydroxymethylanthracene.
Compound C thus obtained can be used in a composition for an anti-reflective or radiation absorbing coating as such or by blending with a film forming material. When the compound C is used in the composition, there is some possibility of evaporation as well as leaching of the compound C in the photoresist. Therefore it is preferable to use the compound after polymerization according to the following Reaction Scheme II to yield a high molecular weight, film forming material. 
Wherein R, R1, X, Y and D are as defined above.
Compound C can also be copolymerized with one or more monomers to impart different functions to the obtained polymeric material such as increased radiation absorption, etch rate, solubility in a particular solvent, shelf-life stability, curing (cross-linking) property and other property improvement as shown in reaction scheme III. For example, suitable comonomers to impart solubility to the polymers are usually acrylates, methacrylates and so on and suitable ones to raise the Tg value of polymers are styrene and its derivatives. Specific comonomers to impart suitable properties to polymers are methyl methacrylate, 2-hydroxyethyl methacrylate, ethyl methacrylate, methyl acrylate, 2-(methacryloyloxy)ethyl. methacrylate, acrylic acid, acrylonitrile, acrylamide, 2-isocyanatoethyl methacrylate, 4-acetoxystyrene, 3-methyl-4-hydroxystyrene, styrene, vinyl chloride, ethyl vinyl ether, butyl vinyl ether, isobutyl vinyl ether, cyclohexyl vinyl ether, methyl vinyl ether, maleic anhydride, maleimide, N-substituted maleimides, vinyl acetate and 2-isocyanatoethyl acrylate. Examples of comonomers classified under every property are as follows. That is, comonomers for increasing radiation absorption when used with organic chromophores include 2-isocyanatoethyl methacrylate, maleic anhydride, maleimide, N-substituted maleimides, 2-isocyanatoethyl acrylate and soon, comonomers for increasing etch rate are methyl methacrylate, 2-hydroxyethyl methacrylate, ethyl methacrylate, methyl acrylate, acrylic acid, vinyl chloride and so on; comonomers for improving solubility in usual photoresist solvent such as PGMEA and, ethyl lactate include 2-(methacryloyloxy)ethyl methacrylate, acrylic acid, 4-acetoxystyrene, 3-methyl-4-hydroxystyrene, ethyl vinyl ether, butyl vinyl ether, isobutyl vinyl ether, cyclohexyl vinyl ether, methyl vinyl ether, vinyl acetate and so on; comonomeres for improving curing (cross-linking) property include 2-isocyanatoethyl methacrylate, 2-isocyanatoethyl acrylate and so on; and comonomers for raising Tg value include styrene, 3-methyl-4-hydroxystyrene and so on. However, the above described specific compounds and properties are only illustrative and not limited to these groups of compounds. Any comonomers represented by General Formulas in the following Reaction Scheme III can be used. 
Wherein R, R1, R2, R3, D, X, Y and Z are as defined above, and n, p and q are simple integers including zero and m and o are also simple integers including zero while at least one of them is greater than zero.
As shown above, according to the present invention, the polymeric,dyes can be synthesized by homopolymerization of monomeric dyes shown as the compound C or copolymerization of it with comonomers. Further, the polymeric dyes can also be synthesized by reacted polymers containing isocyanate or thioisocyanate groups in a side chain with an amino or hydroxyl group containing chromophore (D-YH) as shown in the following Reaction Scheme IV. 
Wherein R, R1, R2, R3, D, X, Y and Z are as defined above, n, p and q are simple integers including zero and m and o are simple integers greater than zero.
Yet another aspect of the present invention is that compound A (represented by General Formula III) possessing isocyanate and/or thioisocyanate groups or polymers prepared by polymerization of monomers containing compound A as shown in following reaction scheme V can be used in a composition for an anti-reflective coating or a radiation absorbing coating to impart a cross-linking or hardening function. Incorporation of such functions help to prevent the intermixing as well as diffusion of acid generated in positive-working photoresist into the anti-reflective coating or radiation absorbing coating leading to complete removal of photoresist material upon development process. It is also possible to use isocyanate or thioisocyanate containing monomers or polymers to blend with other polymeric dyes and/or monomeric dyes in order to harden the anti-reflective coating material upon baking. These isocyanate or thioisocyanate containing polymers or monomers are usually able to cure the anti-reflective coating or radiation absorbing coating by using 0.1-40% of the sum of the moles of monomer and monomer unit of polymer containing isocyanate or thioisocyanate groups based on the sum of the moles of monomers and monomer units of polymer in the anti-reflective coating or radiation absorbing coating. As described, blocked isocyanate or thioisocyanate group containing monomer and polymer show the same curing function as non-blocked ones. Therefore the blocked ones are equally treated with the non-blocked ones when used as an additive. 
Wherein R, R1, R2, R3, X and Z are as defined above, m is a simple integer above zero and n, p and q are any simple integers including zero.
Further, anti-reflective coatings (BARC) consisting of film forming polymer chemically connected with dyes are proposed. As materials used for constructing these anti-reflective coatings, for example, polymers in which acid anhydride moieties are reacted with dyes containing an amino group are known. But as all of the dyes do not react, free amines remain in the anti-reflective coating. In the case of using a chemically amplified resist as a photoresist, the remaining amine in the anti-reflective coating reacts with the acid generated in the photoresist by exposure to cause the footing. When polymers reacted with hydroxyl group containing dyes are used, the hydroxyl group containing dyes remain in the anti-reflective coating and footing may occur as when using amino group containing dyes. Adding polymers and/or monomers containing isocyanate or thioisocyanate groups represented by General Formula II or III to anti-reflective coating containing a free amine or hydroxyl group containing compound helps to prevent the footing problem due to binding of the free amine or hydroxyl group containing compound with isocyanate or thioisocyanate groups in polymers or monomers.
Isocyanate or thioisocyanate group containing monomers and/or polymers have a relatively good shelf-life. However as activity of the isocyanate or thioisocyanate group is high, the isocyanate or thioisocyanate group containing coatings suffer from the problem of cross-linking and deterioration with time. When compounds represented by General Formula R7xe2x80x94OH (wherein R7 represents a substituted or non-substituted linear or branched alkyl group, a substituted or non-substituted cyclohexyl group or a substituted or non-substituted phenyl group which are bonded directly or through an alkylene group such as a methylene group) are added to these monomers and/or polymers, the isocyanate or thioisocyanate group change to the General Formula xe2x80x94NHCOOR7 or xe2x80x94NHCSOR7to be blocked. Therefore, the high activity of isocyanate or thioisocyanate groups is controlled and the shelf-life of the composition containing monomers or polymers with these groups is improved. By the process of blocking of isocyanate or thioisocyanate groups, it is possible to improve the shelf-life of the compound as well as to conduct easy refining of monomers or polymers. It is also possible to improve solubility in solvents. After the composition containing monomers or polymers with blocked isocyanate or thioisocyanate group is coated as an anti-reflective coating or radiation absorbing coating and then baked , it results in curing or cross-linking as well as non-blocked ones. Therefore it is thought that a blocked isocyanate or thioisocyanate group acts for curing or cross-linking. The blocking of isocyanate or thioisocyanate groups maybe one part or all of the isocyanate or thioisocyanate group. Polymers where the isocyanate or thioisocyanate group is blocked are represented by following General Formula V. 
Wherein R, R1, R2, R3, R7, D, X, Y and Z are as defined above, m, n, o, p and q are any simple integers including zero and r is a simple integer greater than zero.
According to the present invention, a polymerization process can be carried out in a suitable solvent either using free radical or ionic initiators. The copolymer may be any copolymer structure such as a random copolymer, block copolymer and so on. Preferred solvents to carry out the polymerization include toluene, tetrahydrofuran, benzene, dimethylformamide, dimethyl sulfoxide, ethyl lactate, propylene glycol monomethyl ether acetate (PGMEA) and so on. These solvents can be used individually or by combination of two or more.
Illustrative initiators include but are not restricted to 2,2xe2x80x2-azobis(isobutyronitrile) (AIBN), 2,2xe2x80x2-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2-azobis(2-cyclopropylpropionitrile), 2,2xe2x80x2-azobis(2,4-dimethylvaleronitrile), 2,2xe2x80x2-azobis(2,4-dimethylpentanenitrile), 1,1xe2x80x2-azobis(cyclohexanecarbonitrile), benzoyl peroxide, t-butyl peroxybenzoate, di-t-butyl diperoxyphthalate, t-butyl peroxy-2-ethylhexanoate, t-butyl peroxypivalate, t-amylperoxypivalate, butyl lithium.
Solvent upon synthesis of polymeric dyes according to reaction scheme IV include cyclopentanone, cyclohexanone, butyrolactone, propylene glycol, monomethyl ether acetate, 2-heptanone, ethyl lactate, ethyl-3-ethoxypropionate, ethylene glycol monoethyl acetate, methyl-3-methoxypropionate and so on. These solvents can be used individually or by blending two or more.
The polymeric dyes are isolated from the solvent and, dissolved in a suitable solvent to prepare a composition for an anti-reflective or radiation absorbing coating. If the solvent upon synthesizing the polymeric dye is usable for the anti-reflective or radiation absorbing coating composition, the reaction composition can be used directly without isolating of polymers for preparing the anti-reflective or radiation absorbing coating composition or be coated directly onto a substrate such as wafer. It is preferred to filter the anti-reflective coating or radiation absorbing coating with, for example, 0.5 and 0.2 micron filters and remove insoluble minute particles. The filtrate can be applied directly onto a substrate, for example, a wafer and baked at 50 to 250xc2x0 C. to form an anti-reflective coating or a radiation absorbing coating. However the filter used for filtering is not limited to the above described ones. It need scarcely without saying that any polarized filters are usable, if necessary.
The molecular weights of the homo- or copolymers prepared in reaction schemes II to V range between 500 to 5,000,000 daltons with respect to standard polystyrene as measured on a gel-permeation chromatography (GPC). Preferred molecular weight lies between 3,000 and 100,000 daltons considering the film forming property, solubility characteristics and thermal stability. The molecular weights of the obtained polymers depend on the polymerization conditions such as polymerization time, temperature, monomer and initiator concentration, reaction medium, and can be easily controlled by proper selection or adjustment of these parameters. Narrow molecular weight distribution can also be obtained by choosing ionic polymerization.
The mole ratio of the comonomers in Reaction Schemes III, IV and V depends on the reaction rates of the respective monomers as well as the reaction conditions used and the mole ratio used in the reaction feed. The absorption at the desired wavelength and the refractive index of the final polymer play an important role in the applicability of the polymer for bottom-anti reflective coatings and the like. Absorption in the range of 2 to 40 per micron film thickness is desired and between 5 and 25 is especially preferred and should be maintained in the copolymers as well. Too high an absorption and too low an absorption may lead to bad performance of the anti-reflective coating. Also the required radiation absorption property for an anti-reflective coating material depends on the radiation absorption property and refractive index of the photoresist material applied on the anti-reflective coating. The refractive index of the anti-reflective coating would be the best if it exactly matches or at least is very close to that of the resist layer applied on top. The radiation absorbing property of an anti-reflective coating material depends on the molecular extinction coefficient of the monomer containing chromophore and it""s mole ratio. Therefore the mole percent of the monomer containing the chromophore is important to control the absorption property. This can be easily controlled or tailored in the present invention as shown in reaction schemes III or IV to prepare polymers having the desired mole ratio.
The composition for an anti-reflective coating or a radiation absorbing coating of the present invention contain one or more solvents. The anti-reflective coating and radiation absorbing coating material are dissolved in a solvent for the composition. The solubility of the anti-reflective coating materials and radiation absorbing coating materials in safe solvents are also important in its application as an anti-reflective coating or a radiation absorbing coating. This is not restricted to safety considerations as long as the solvent can dissolve the anti-reflective coating or radiation absorbing coating material and other additives (surfactants, plasticizers, cross-linkers, etc.) to improve the film forming properties. From the standpoint of safety, solubility, boiling point and film formation, examples of preferred solvents may include propylene glycol monomethyl ether acetate (PGMEA), ethyl lactate (EL), cyclohexanone, cyclopentanone, 2-heptanone and the like and combinations thereof. Solubility of the anti-reflective coating or radiation absorbing coating material of the present invention itself can be controlled by properly choosing suitable comonomers as shown in reaction schemes III, IV and V.
Apart from the dye compounds and solvent described above, the composition for an anti-reflective or radiation absorbing coating may also contain surfactants and other additives to form a uniform, defect free anti-reflective coating or radiation absorbing coating on the semiconductor substrate on which the composition is applied. As examples of surfactants, fluorinated or siloxane compounds can be illustrated but usable surfactants are not limited to these groups of compounds.
Another property required for the polymer for a bottom anti-reflective coating is the etch rate of the coating. Skilled artists in the semiconductor industry will appreciate a bottom anti-reflective coating material that has significantly higher etch rate than the resist itself, in order to successfully transfer the pattern after exposure and further processing steps. This property of the polymer can also be controlled by properly selecting the comonomers in the Reaction Schemes III, IV and V. In general aromatic compounds have poor etch rates. Therefore, as comonomers, aliphatic group containing monomers as well as monomers possessing non-carbon elements such as oxygen, nitrogen, or halogen atom are preferably incorporated to increase the etch rate.
The glass transition temperature (Tg) of the anti-reflective coating or radiation absorbing coating material plays an important role in the intermixing property of the anti-reflective coating or radiation absorbing coating and the photoresist applied thereon. Intermixing of the coating and the photoresist would lead to incomplete removal of the photoresist upon development. Yet another problem when a chemically amplified photoresist material is applied on an anti-reflective coating or radiation absorbing coating material with low Tg is that the acid formed in photoresist upon exposure may diffuse into the BARC layer, which leads to a distorted latent acid image and can also cause incomplete removal of the photoresist material upon development. Therefore, it is desirable that the anti-reflective coating or radiation absorbing coating material has a glass transition temperature at least above the maximum processing temperature, such as the baking temperature used, while forming the photoresist layer. Again the glass transition temperature of the polymers of the present invention can be controlled by choosing the appropriate type and amounts of monomers shown in Reaction Schemes III, IV and V.
The preferred examples of polymers represented by General Formula II which can use in a composition for an anti-reflective coating or a radiation absorbing coating of the present invention include those represented by the following General 
Wherein R8 is a hydrogen atom or a methyl group, R2 is a phenyl group, xe2x80x94COOH, a halogen atom, a cyano group, an alkoxyl group or xe2x80x94COOR6 in which R6 is a substituted or non-substituted alkyl or aryl group or an ethylacetoacetate group; R3 is xe2x80x94COOD; D is an organic chromophore which absorbs the exposed wavelength (100-450 nm) and represents a substituted or non-substituted benzene ring, condensed ring or heterocyclic ring bonded directly or through an alkylene group, Z is O, ND group or NR5 group in which R5 is either a hydrogen atom or a substituted or non-substituted, phenyl group or cyclic, linear or branched alkyl group and m, n, o, p and q are simple integers including zero and at least one of m and o is greater than zero. 
Wherein R8 is a hydrogen atom or a methyl group, R2 is a phenyl group, xe2x80x94COOH, a halogen atom, a cyano group, an alkoxyl group or xe2x80x94COOR6 in which R6 is a substituted or non-substituted alkyl or aryl group or an ethylacetoacetate group, R3 is xe2x80x94COOD, D is an organic chromophore which absorbs the exposed wavelength (100-450 nm) and represents a substituted or non-substituted, benzene ring, condensed ring or heterocyclic ring bonded directly or through an alkylene group, R4 is either a hydrogen atom or a substituted or non-substituted, phenyl group or cyclic, linear or branched alkyl group, Z is O, ND group or NR5 group in which R5 is either a hydrogen atom or a substituted or non-substituted, phenyl group or cyclic, linear or branched alkyl group and m, n, o, p and q are simple integers including zero and at least one of m and o is greater than zero.
In above described General Formula IIxe2x80x2 or IIxe2x80x3, preferred examples of m, n, o, p and q include that;
(1) m, n, p and q are zero and o is between 5 to 50,000,
(2) n, p and q are zero, sum of m and o is between 5 to 50,000 and mol fraction of m is between 0.05 to 0.95,
(3) m, p and q are zero, sum of n and o is between 5 to 50,000 and mol fraction of n is between 0.05 to 0.95,
(4) p and q are zero, sum of m, n and o is between 5 to 50,000 and mol fraction of n is between 0.05 to 0.95,
(5) n, o and p are zero, sum of m and q is between 5 to 50,000 and mol fraction of q is between 0.05 to 0.50,
(6) n, o and q are zero, sum of m and p is between 5 to 50,000 and mol fraction of m is between 0.05 to 0.90, and
(7) q is zero and sum of m, n, o and p is between 5 to 50,000.
In case of above (1) and (3), polymers in which R2 is xe2x80x94COOR6 where R6 is a methyl group, an ethyl group, a t-butyl group, an isopropyl group, an ethylacetoacetate group, a 2-hydroxyethyl group or an n-butyl group are more preferred.
The anti-reflective coating or radiation absorbing coating materials of the present invention can be used for both positive- and negative-working resist materials. Therefore any resist known for ever can be used and all of them should successfully form images with no standing waves and no reflective notching depending on reflecting, no intermixing and no diffusion of photo-generated acid based on hardening of the coating, good developing and high resolution. In the point of view of resolution of resist image formed, as a resist, a chemically amplified resist and quinone diazide type resist is preferred. The exposure is conducted by using radiation in the range of 100 and 450 nm wavelength as the radiation source.
In the present description, when a number of substituents are shown by the same designation, for example, R, R1, R8, D, X, etc. exist in one General Formula, each substituent showed by the same designation in the General Formula can be selected individually from among atoms or groups comprising the substituent and be the same or different atoms or groups.